A safety glass is used for automobiles, etc., with a structure that a laminated glass is formed by sandwiching an intermediate layer including polyvinyl acetal resin, etc., between opposed plurality of (for example, two) glass sheets, and further there is proposed a structure for the purpose of reducing a cooling load or a human feeling of heat by blocking a solar energy incident on a laminated glass having a heat-ray shielding function in the intermediate layer.
For example, patent literature 1 discloses a laminated glass with a soft resin layer containing heat-ray shielding metal oxide composed of tin oxide or indium oxide with a fine particle diameter of 0.1 micrometer or less, sandwiched between two opposed glass sheets.
Further, patent literature 2 discloses a laminated glass with an intermediate layer sandwiched between at least two opposed glass sheets, wherein metal such as Sn, Ti, Si, Zn, Zr, Fe, Al, Cr, Co, Ce, In, Ni, Ag, Cu, Pt, Mn, Ta, W, V, and Mo, oxide of the metal, nitride of the metal, sulfide of the metal, Sb or F-doped metal, or composite of them are dispersed in the intermediate layer.
Further, patent literature 3 discloses a window glass for automobiles with fine particles composed of TiO2, ZrO2, SnO2, and In2O3, a glass component composed of organosilicon or organic silicon compound, sandwiched between opposed transparent plate-like members.
Further, patent literature 4 discloses a laminated glass with an intermediate layer composed of three layers, provided between at least two opposed transparent glass sheets, wherein metal such as Sn, Ti, Si, Zn, Zr, Fe, Al, Cr, Co, In, Ni, Ag, Cu, Pt, Mn, Ta, W, V, Mo, oxide of the metal, nitride of the metal, sulfide of the metal, and Sb or F-doped metal, or the composite of them is dispersed in a second layer of the intermediate layer, and the intermediate layer between a first layer and a third layer is formed as a resin layer.
However, conventional laminated glasses disclosed in patent literature 1 to 4 involve a problem that a heat-ray shielding function is not sufficient when a high visible light transmittance is desired.
Meanwhile, in patent literature 5, an applicant discloses a heat-ray shielding laminated glass formed by including the intermediate layer having a heat-ray shielding function provided between two glass sheets, with this intermediate layer formed by a heat-ray shielding film containing hexaboride fine particles alone, or hexaboride fine particles and ITO fine particles and/or ATO fine particles, and vinyl resin, or discloses a heat-ray shielding laminated glass wherein the intermediate layer is formed by a heat-ray shielding film containing the fine particles on a surface facing inside of at least one of the glass sheets, and a heat-ray shielding film containing vinyl resin interposed between the two glass sheets.
As is described in patent literature 5, according to optical characteristics of the heat-ray shielding laminated glass to which the hexaboride fine particles alone, or hexaboride fine particles and ITO fine particles and/or ATO fine particles are applied, a maximum transmittance is exhibited in a visible light region, and a strong absorption is exhibited in a near infrared region, thus exhibiting a minimum transmittance in the near infrared region. As a result, the heat-ray shielding laminated glass of the present invention is improved to 50% range of the solar transmittance when the visible light transmittance is 70% or more, compared with conventional laminated glasses described in patent literature 1 to 4.
Meanwhile, as the fine particles having a shielding function in the near infrared region, composite tungsten oxide fine particles are known in addition to the aforementioned ITO fine particles, ATO fine particles, and hexaboride fine particles. In patent literature 6, inventors of the present invention disclose a heat-ray shielding laminated glass wherein polyvinyl acetal resin is replaced with ultraviolet curing resin, so that the intermediate layer is formed by a heat-ray shielding film containing a composite tungsten compound and hexaboride in the ultraviolet curing resin.